People at elevated positions above a floor or other relatively lower surface are at risk of falling and injury. For example, workers and other personnel who have occupations that require them to be at elevated positions, such as on scaffolding, are at risk of falling and injury. Safety harnesses are often worn to stop a person's fall and prevent or reduce injury.
Safety harnesses typically have a harness portion worn by the user and a tether or lanyard extending from the harness portion. The lanyard connects the harness portion to a secure structure. If a person falls from the elevated position, the safety harness stops the person's fall when the lanyard is straightened.
A load limiter on a seat belt system can be worn to secure the occupant of a vehicle in the event of a sudden stop or collision to reduce the risk of injury. If a person is subjected to inertia due to a vehicle's sudden stop, the load limiter limits the forces felt by the person during the person's forward movement and also limits the person's forward movement when the load limiter is extended.
Lanyards that attempt to absorb the shock of a person's fall or sudden stop are known. Current lanyards have been made from two separate webbings assembled together. One webbing is a narrow, flat webbing woven of partially oriented yarn (POY webbing) and the other webbing is a relatively higher strength tubular-shaped webbing. After manufacture of the two webbings, the POY webbing is inserted into one end of the tubular-shaped webbing and pulled through the tubular-shaped webbing. A hook or other device inserted into the opposite end of the tubular-shaped webbing is then used to pull the POY webbing through the tubular-shaped webbing so that the POY webbing extends inside of the tubular-shaped webbing from one end to the opposite end. The relative lengths of the POY webbing and the tubular-shaped webbing then must be adjusted. To adjust the relative lengths, while holding the POY webbing in place, one end of the tubular-shaped webbing is moved closer to the opposite end to place the tubular-shaped webbing in an accordion-like position over the POY webbing. The relative length adjustment of the webbings is performed manually and is a significant disadvantage of existing lanyards. After the manual adjustment of the relative webbing lengths, the POY webbing is essentially in a straight, linear orientation inside of the accordion-shaped orientation of the tubular-shaped webbing. The two webbings are then attached to each other by sewing at the ends. Any excess POY webbing extending out of the ends of the tubular-shaped webbing is cut off and discarded.
Because conventional lanyards are made from two separate webbings that must be assembled together, manufacture of the lanyards requires costly and tedious assembly processes, such as inserting the POY webbing through the tubular-shaped webbing. Moreover, after the insertion process, an additional manual process is required that adjusts the relative webbing lengths by placing the tubular-shaped webbing in the accordion position while maintaining the POY webbing in a straight position. Then, another process is required to attach the two separate webbings together while maintaining the POY webbing in the straight position and the tubular-shaped webbing in the accordion-shaped position. The relative lengths of the POY webbing and the tubular-shaped webbing is critical for proper functioning of the lanyard. The manufacturing process is complicated by proper control and manual setting of the critical relative lengths of the two webbings.
In addition, existing lanyards using POY webbings have a constant deployment force, which refers to the energy absorption or energy dissipation rate provided by the webbing. A deployment force is often shown in graphical form as the applied force to a load. Deployment force is determined by the number of POY yarns in the lanyard. Because the deployment force of existing lanyards is constant and consistent throughout deployment, the lanyard is not well suited for all types of users. For example, a lanyard having a relatively high deployment force may not be suitable for use with a child, who would experience more shock associated with a fall or sudden stop if the force of the fall or stop was not enough to activate the shock absorbing feature of the lanyard. Similarly, a lanyard having a relatively low deployment force may not be suitable for use with a heavy user if the configuration of the lanyard is not sufficient to stop the fall or limit forward movement.
Existing lanyards that purport to reduce shock can be found in U.S. Pat. Nos. 5,113,981; 6,085,802; 6,390,234; and 6,533,066 and WIPO Publication No. WO/01/026738.